diff --git a/package/mac/build-mac-nightly-dmg.rb b/package/mac/build-mac-nightly-dmg.rb
index 212c54cdb..674120868 100755
--- a/package/mac/build-mac-nightly-dmg.rb
+++ b/package/mac/build-mac-nightly-dmg.rb
@@ -15,8 +15,8 @@ osgVersion = runOsgVersion('version-number')
 $osgSoVersion=runOsgVersion('so-number')
 $openThreadsSoVersion=runOsgVersion('openthreads-soversion-number')
 
-codeSignIdentity = ENV['FG_CODESIGN_IDENTITY']
-puts "Code signing identity is #{codeSignIdentity}"
+$codeSignIdentity = ENV['FG_CODESIGN_IDENTITY']
+puts "Code signing identity is #{$codeSignIdentity}"
 
 puts "osgVersion=#{osgVersion}, so-number=#{$osgSoVersion}"
 
@@ -81,7 +81,7 @@ end
 
 def code_sign(path)
   puts "Signing #{path}"
-  `codesign -s "#{codeSignIdentity}" #{path}`
+  `codesign -s "#{$codeSignIdentity}" #{path}`
 end
 
 fgVersion = File.read("#{srcDir}/version").strip